// 原型链的最顶端是 Object
function Parent() {

}

var p = new Parent()

console.log(p.__proto__ === Parent.prototype) // true
const proto = p.__proto__
console.log(proto.constructor) // Funtion Parent
console.log(proto.__proto__.constructor) // [Function: Object]
console.log(proto.__proto__.__proto__) // null


console.log(Parent.__proto__.constructor) // [Function: Function]
console.log(Parent.__proto__.__proto__.constructor) // [Function: Object]
console.log(Parent.__proto__.__proto__.__proto__) // null